Electric welding system.



A. D. KEENE. ELECTRIC WELDING SYSTEM.

APPLICATION FILED MAYI. I916- 1 ,2 46,106. Patented N0v.'13, 1917.

Inventor:

Alvin Dheene,

His Attcprneg UNITED STATES PATENT OFFICE.

ALVIN n. mama, orscnnnno'ranxnnw YORK, ASSIGNOR T0 GENERAL EnEc'rmc com any, A CORPORATION or NEW YORK.

Emcrnrc WELDING SYSTEM.

Application filed may 1, 1916. Serial No. 94,628.

To all whom 2% may concern: a

Be it known that I, ALVIN D. KEENEfH citizen of the United States, residing at Schenectady, in the county of Schenectady, State of New 'York, have invented certain new and useful Improvements in Electric Welding Systems,- of which the following is a specification.

, .Myxinvention' relates to welding systems, particularly to electric arc welding systems. One object of my invention is to provide a system in'yvhich the overload protective device operates at substantiall a constant per cent overload although, i desired, the

-character of the load itself may be changed with a' consequent change of normal load current.

To' this end the overload protective dev1ce is controlled by'an increase of voltage drop 20 across the regulating rheostat. Preferably a controlling solenoid thereof is connected across that rheostat. Other necessary or desirable resistances may be' included in the system. Particularly to take care of. abrupt and substantial changes in the resistance at the work, as by the substitution of metal for carbon electrodes or .viceversa in arc weld ing systems, I provide means for increasing and decreasing the 'eflect of the voltage drop on the protective device as by providing a resistance member which may be, included in circuit with the controlling solenoid as the occasion requires.

My invention will be better understood from the following description of theembodiment of-it in.the arc welding system diagrammatically illustrated in the single figure of the accompanying drawing.

The generator 1 which is compound wound is the s'ourceof electrical energy. The are is drawnbetween the ele rode'2 and the work 8 and constitutes'iid load, the electrode and work being res ectively connected to opposite sides of the generator and the work constituting one of the electrodes. An automatically operated circuit breaker 4 may be used between the generator and the load at 2 and 3 to open the circuit on such overloads on the generator as do not affect the protective device later described." Between the load and the source is the rheostat 5 for regulating the amount of current supplied to load. A resistance 6 may be used in addition to limit the'amount of current which can be supplied to the load with the rheo- -connected to the system at 16 acted upon by a voltage proportional to the potential difference across that rheostat at each instant; one side of the solenoid 15 is on'the gen'- erator side of the contactor 12 and on the other side is provided with two connections to the rheostatarm 7 pne connection 20 being made to the conducting portion -8 of the circular contact on therheostatythe other connection 21'being made through a resistance 22 direct to the arm of the rheostat. \Vhen the solenoid 15 raises its armature, it

opens the circuit tlirouglfthe solenoid 14 the contactor 12 opens the and thereupon welding circuit. Since the solenoid 14 is connected across the generator 1 as shown the contactor 12 closes the welding circuit so long as the relay 13is closed irrespective of whether the circuit is completed at the load. \Vith the rheostat arm 7 in engagement with the portion 8 of the rheostat circular' contact, the resistance 22 is in effect out of the circuit through the solenoid 15',

A manually operated switch 23 is provided for short-circuiting the resistance 22 when desired as hereinafter indicated.

The rheostat circular contact is so related to the rheostat arm that when that arm? is in engagement with any of the low resistance points of the rheostat usually used for working with a carbon electrode. it is also in engagement with the conducting polti n 8 of the circular contact; corrcspondin y when the rheostat arm 7 is in engagcm nt with the higher resistance points of he being short-circuited'by the connection 20.

rheostat usually used when working wit a metal electrode. the arm 7' is in engagement with the insulated portion 9 of the circular insulated portion 9 of the circular contact may be omitted so far as the operation of my invention is concerned but'for mccl1anicontact. As will be understood later, the

cal reasons it is sometimes desirable to employ this insulated portion 9 rather than omit this portion altogether.

The solenoid 15 is designed to raise its "armature and open the welding circuit on carbonarc is varied materially by such an arc movement If the system were to be employed with but one type of load, as a carbon electrode and are exclusively, the resistance 22 and insulated portion 9 of the circular contact might be altogether omitted and the solenoid 15 connected directly to.

the rheostat arm 7. If, however, a substantial change is made in the resistance at the load as when a metallic electrode is substituted for the carbon electrode, the armature of the solenoid 15 is raised at a materially ditl'erent percent of overload due to this difference in resistances, and hence to the difference between the parts of the total voltage consumed in the rheostat in the two cases unless some arrangement is made to counteract this efi'ect. The resistance of drawn to a metal electrode is'considerably less, relatively speaking, than the resistance of an are drawn to a carbon elec trode. Due to this difference in resistances the rheostat is usually operated on higher.

resistance points when metallic electrodes are used as hereinbefore indicated. In order that the same system may be used for either carbon or metallic electrodes, the reslstance 22 is provided and is included in.

the circuit through the solenoid 15 when the rheostat is operated on the hi her resistance pointsusually used for meta lie electrodes. This resistance 22 decreases the effect of the voltage drop across the rheostat on the solenoid 15 to an extent corresponding to the increase in that voltage dro resulting from the substitution of a metal ic electrode for l the carbon electrode. After thesubstitution of the metallic electrode therefore, the protective device continues to operate at something like the original percent overload; in

other words, the current supplied to the metallic, arc may be changed in value by changing thesetting of the rheostat as before without departing -to an impractical extent from this percent overload for the operation of the protective device.

At times it may be desired to operate a carbon electrode at a lower current value than is possible by the system so 1ar described, for the resistance 22 (and the insulated portion 9 of the circular contact) limits the movement of the arm 7 with a carbon are; after any movement of the arm 7 which'includes the'resistancc 22 in the circuit through the solenoid 15, this solenoid operates (with a carbon electrode and are) only at a considerable higher value of percent overload than is desired. To take care of. this fairly unusual case, the manually operated switch 23 is provided. With this switch closed the carbon electrode may be used with unusually low value of current, the'solenoid 15 picking'up its armature at substantially the desired percent overload while the rheostat is operated over its full range.

While I have described the principle of my invention and the best mode I have contemplated for applying'this principle, other modifications will occur to those skilled in this art and I aim in the a pended claims to cover all modifications which do not in volve a departure from the spirit and scope of my invention.

\Vhat I claim as new and desire to secure by Letters Patent of the United States, is

1. A welding system comprising a source of energy, means-for connecting the same to a welding load, a rheostat in said connecting means, and a protective device responsive to a variation of voltage between the terminals of said rheostat. I

2. An arc welding system comprising a' source of energy, electrodes connected thereto, a rheostat between said electrodes and source, and means for reducing the sup'ply of energy to the electrodes responsive to a predetermined increase of voltage drop across said rheostat.

3. A welding system comprising a. source of energy, electrodes connected thereto, a rheostat controlling the supply of energy to said electrodes, and protective means controlled by an increase of potential ditierence across said rheostat above a predetermined value.

4. Anarc welding system comprising a source of char ,'electrodes connected thereto, a rheostat tween said electrodes and source, means for reducing the supply o.-' energy to said electrodes, and a Solenoid con-' trolling said means connected to the circuitat opposite sides of the rheostat. 5. A welding systemcom'prising a source of energy, electrodes connected thereto: a rheostat between said electrodes and source,

means for reducing the supply of energy to said electrodes, a solenoid controlling said means connected to the circuit at opposite sides of the rheostat, and means for increasing and decreasing the resistance in the connections between said solenoid and the c i'r-- cuit.

6. .-\n arc welding system comprising a source of energy. electrodes connected there to, a rheostat between sanl electrodes and source, means for reducing the supply ofenergy to said electrm'lcs. a solenoid controlling said means connected to the Welding circuit at opposite sides'of the rbeostat, a resistance, and means for inserting said resistance in circuit with saidfsolenoid between said solenoid and the welding circuit.

7. An arc welding system comprising a,

to, a rheostat between said electrodes and source, means for rediicingthe supply of energy to said ele ctrodcs esponsivetpmn otential diflerencc across said and do-" increase of rhcnstat, an means forincreasing creasing the efl'cct of such potential difference on the energy reducing means. j

9. A welding system comprising a source l my handthis 29th day oifApril 1916s of energy, weldingf electrodes connected thereto, a rheostat connected in series with said electrodes, means for automatically re -comprising a contactor in series with rheostat and a magnet operatively connected 50 I ducing the supply of energy to said electrodes responsive to .a predetermined increase of otentiaIdiEeI-ence across said rlieostat, a resistance having one terminal connected to said reducing means and a connection for automatically lacing said re- 'sistance in series with said rheostat when the 40 settin of the rheostat exceeds a predeterxnin value.

10. A weldin system comprising a source of energy, a w cling' circuit'connected thereto; a series rheostat in said circuit having a. movable member 'in contact with a stationary conductin member over the lower range of the -r eostat, a protective devicg to said contactorg'a c6ntrolling ma at 0011- nectod to o to said protective evice, a. connection tween one terminal of said controllingma at and aipoint intermediate said an said rhebstat a circuit connection'bctwpen the opposite terminal of s'aidjcontrollmg magnet and the stationary- .condiictingi-fmember ofsaid rheosta a '-'second circuit';oonnsction betfieen the ast mentioliedtcrminal of the oontrollin' magnet'and-the movable member of the" r eostat ands resistance in said'second connection.

' In witness -whereof, .1 have hereunto set .ALVIN 1). 

